1. Field of the Art
The present invention relates in general to a mounting device for resiliently supporting an engine on a frame of a front-engine front-drive automotive vehicle such that the engine is disposed transversely in the vehicle. More particularly, the invention is concerned with a resilient mounting structure for such a transverse engine, including a cylindrical resilient bushing or mount which comprises an inner sleeve, an outer sleeve and a resilient member connecting the inner and outer sleeves. The resilient mount is disposed parallel to an axis of rolling of the transverse engine which extends transversely in the vehicle.
2. Related Art Statement
For resiliently mounting such a transversely oriented engine of a front-engine front-drive car, an engine mounting device is known, which is disposed in parallel with an axis of rolling of the engine which extends across the length of the car. Such an engine mounting device uses a cylindrical resilient bushing or mount which comprises an inner sleeve, an outer sleeve disposed around the inner sleeve in a radially-spaced apart and parallel relationship with each other so as to form a radial space therebetween, and a resilient member disposed in the radial space to resiliently connect the inner and outer sleeves. The inner sleeve is connected to one of the engine and the car frame via a shaft inserted therein, while the outer sleeve is connected at its outer periphery to the other of the engine and the frame. The resilient member interposed between the inner and outer sleeves includes two voids or cavities which are formed on diametrically opposite sides of the inner sleeve.
In the known engine mounting device of the type described above, the resilient mount is disposed between the car frame and the engine such that the two voids formed in the resilient member are opposite to each other in the vertical direction of the car. That is, the direction in which the two voids are opposite to each other diametrically in the cylindrical resilient mount is held upright, with one of the voids being located right above the inner sleeve. In this arrangement, the resilient member is subjected primarily to a shearing stress when a vibrational load is applied to the resilient mount in the vertical direction. On the other hand, the resilient member is subject to a considerable degree of compressive stress in addition to the shearing stress, when a vibrational load is applied in the direction of rolling of the engine. Accordingly, the resilient member has a low spring rate or low spring constant in the vertical direction of the car, but has a comparatively high spring constant in the rolling direction. These spring characteristics of the conventional engine mounting device are not favorable for supporting a transversely oriented engine of a front-engine front-drive car.
Described more particularly, the comparatively low spring constant of the resilient member in the vertical direction may allow the engine to vibrate due to vibrations of unsprung members of the car caused by bumpy road surfaces, namely, may easily cause a phenomenon of engine "shake". In the meantime, the comparatively high spring constant in the rolling direction may lead to easy transfer of idling or other vibrations of the engine about its torque axis to the car frame.